<?php

namespace weixin;

class JSDK
{
    private $appId;
    private $appSecret;

    public function __construct($appId, $appSecret)
    {
        $this->appId = $appId;
        $this->appSecret = $appSecret;
    }

    public function getSignPackage()
    {
        $jsapiTicket = $this->getJsApiTicket();
        if($jsapiTicket){
            // 注意 URL 一定要动态获取，不能 hardcode.
            $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://";
            $url = "$protocol$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";

            $timestamp = time();
            $nonceStr = $this->createNonceStr();

            // 这里参数的顺序要按照 key 值 ASCII 码升序排序
            $string = "jsapi_ticket=$jsapiTicket&noncestr=$nonceStr&timestamp=$timestamp&url=$url";

            $signature = sha1($string);

            $signPackage = array(
                "appId" => $this->appId,
                "nonceStr" => $nonceStr,
                "timestamp" => $timestamp,
                "url" => $url,
                "signature" => $signature,
                "rawString" => $string
            );
            return $signPackage;
        }else{
            return;
        }
        
        
    }

    private function createNonceStr($length = 16)
    {
        $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        $str = "";
        for ($i = 0; $i < $length; $i++) {
            $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
        }
        return $str;
    }

    private function getJsApiTicket()
    {
        // jsapi_ticket 应该全局存储与更新，以下代码以写入到文件中做示例
        $data = json_decode($this->get_php_file("jsapi_ticket.php"));
        $ticket="";
        if ($data->expire_time < time()) {
            $accessToken = $this->getAccessToken();
            // 如果是企业号用以下 URL 获取 ticket
            // $url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=$accessToken";
            $url = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?type=jsapi&access_token=$accessToken";
            $res = $this->httpGet($url);
            if(isset($res["ticket"])){
                $ticket = $res["ticket"];
                if ($ticket) {
                    $data->expire_time = time() + 7000;
                    $data->jsapi_ticket = $ticket;
                    $this->set_php_file("jsapi_ticket.php", json_encode($data));
                }
            }
        } else {
            $ticket = $data->jsapi_ticket;
        }

        return $ticket;
    }

    private function getAccessToken()
    {
        // access_token 应该全局存储与更新，以下代码以写入到文件中做示例
        $data = json_decode($this->get_php_file("access_token.php"));
        $access_token="";
        if ($data->expire_time < time()) {
            // 如果是企业号用以下URL获取access_token
            // $url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret";
            $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=$this->appId&secret=$this->appSecret";
            $res = $this->httpGet($url);
            if(isset($res["access_token"])){
                $access_token = $res["access_token"];
                if ($access_token) {
                    $data->expire_time = time() + 7000;
                    $data->access_token = $access_token;
                    $this->set_php_file("access_token.php", json_encode($data));
                }
            }
        } else {
            $access_token = $data->access_token;
        }
        return $access_token;
    }

    private function httpGet($url)
    {
        $ch = curl_init($url);
        //3.设置参数
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);//跳过证书验证
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);  // 从证书中检查SSL加密算法是否存在
        //4.调用接口
        $res = curl_exec($ch);
        if (curl_errno($ch)) {
            var_dump(curl_error($ch));
        }
        $res = json_decode($res, 1);
        return $res;
    }

    private function get_php_file($filename)
    {
        return trim(substr(file_get_contents(ROOT_PATH . "extend/weixin/" . $filename), 15));
    }

    private function set_php_file($filename, $content)
    {
        $fp = fopen(ROOT_PATH . "extend/weixin/" . $filename, "w");
        fwrite($fp, "<?php exit();?>" . $content);
        fclose($fp);
    }
}

